the car's ECU (Engine Check Unit) has logged a fault on the vehicle,in this case it could be a worn drive on the gear shift mechanism You need to take it to a nissan dealer they will plug in whats called a diagnostic PC, it will read whatever fault code the ECU has logged, it will tell the machanic exactly what's wrong with the car, expensive-probably £50-£60 just to plug it in and read the fault code, then repairs on top of that, thats the best solution, hope it helps.
Nissan Mechanic, July 2007